subroutine rks1
use var
implicit none

    integer i,m,j
    real(8) du,dv
    real(8) Qmean_n_k(1:gridsx,4)
    
    
    
    call comput_flux1
    !call comput_flux2    
    call rhs(Qmean,Qmean_n_k)
    do i=1,gridsx
        
        !write(*,'(I4,2X,100(ES12.4,1X))') i, Qmean_n(i,1),flux1(i,1),flux1(i-1,1),Qmean_n_k(i,1)
        Qmean(i,1)=Qmean_n(i,1)-dt*Qmean_n_k(i,1)
        !write(*,'(I4,2X,100(ES12.4,1X))') i, dt,Qmean(i,1),Qmean_n(i,1),Qmean_n_k(i,1),-dt*Qmean_n_k(i,1)
        Qmean(i,2)=Qmean_n(i,2)-dt*Qmean_n_k(i,2)
            
        Qmean(i,3)=Qmean_n(i,3)-dt*Qmean_n_k(i,3)
        
        Qmean(i,4)=Qmean_n(i,4)-dt*Qmean_n_k(i,4)
            
        !Qmean(i,j,4)=Qmean_n(i,j,4)-dt*Qmean_n_k(i,j,4)
            
        !write(*,'(I4,2X,100(ES12.4,1X))')i,j,Qmean(i,j,4)      
    enddo 
    call comput_original_var
    call boundary
    
    
    
    
    

end subroutine 